共查询到20条相似文献,搜索用时 140 毫秒
1.
起爆延时严重影响隧道爆破掘进效率,研究隧道精确控制爆破中岩石的破碎效果和掘进效率具有重要意义。为此,开展了隧道爆破中掏槽孔与辅助孔之间延时的相似模型试验研究,分析了不同起爆延时情况下岩石的破碎特征。模型试验表明,在隧道爆破中精确延时电子雷管对于提高爆破效果具有明显优势,得到了一定条件下模型试验与现场试验中起爆延时的相似关系。由现场试验可知:掏槽孔与辅助孔之间的最佳延时范围为15~25 ms,此时炮孔的利用率最高。结合相似理论的模型试验,得到最佳延时范围为8~24 ms,与现场试验结果具有较好的一致性,研究结果对隧道爆破掏槽孔与辅助孔之间的延时选取具有指导意义。 相似文献
2.
采用飞片碰撞技术,在TNT/RDX(40/60)炸药中获得了2.5倍于正常爆轰的最大超压值,得到了超压爆轰下爆轰产物物态方程p=Aρk+A1(p-pJ)(p-爆压,单位GPa,ρ-密度,单位kg/m3,A=ρJ/ρkJ,pJ=27.06 GPa,ρJ=2.3×103 kg/m3,k=2.77,A1=2.7×10-3 GPa-1,下表J代表正常爆轰状态)。该方程还可以较好地描述超压爆轰产物的二次冲击状态。 相似文献
3.
4.
5.
6.
7.
8.
9.
本文首先建立轮辐栅网结构模型, 分区计算其屏蔽系数和单个栅格内栅丝半径与该栅格面积之比, 结合 Spangenberg书中的结论给出了轮辐栅网截止放大系数的新表达式, 然后详细地研究了栅丝半径、各环区所对球心角以及径向栅丝数目对截止放大系数的影响, 并计算了温度升高之后截止放大系数的变化, 最后给出了设计轮辐栅网的步骤和具体实例. 结果显示, 根据新表达式设计的栅网具有更好的稳定性和可靠性, 能够很好地解决平板正方形栅格近似中存在的问题. 相似文献
10.
11.
爆炸焊接过程会产生爆炸地震、冲击波、有毒气体和噪音等有害效应。设计并制作一个直径为36 m、入口和排烟口直径分别为8 m的半球形结构,用以降低爆炸焊接过程中产生的超压影响。为了研究实际超压降低效果,进行了裸爆和按1/6比例建立的半球形结构内爆炸的超压对比实验。实验结果表明:当超压的传播距离大于20 m时,这种半球形结构能有效降低爆炸焊接过程中产生的超压;对于相同的超压传播距离,切线方向(垂直于半球形结构入口方向)比径向方向(半球形结构入口方向)的超压降低效果好。结合冲击波的传播和反射特点,对超压降低的可能原因进行了分析。 相似文献
12.
Investigation on the relationship between overpressure and sub-harmonic response from encapsulated microbubbles 下载免费PDF全文
Sub-harmonic component generated from microbubbles is proven to be potentially used in noninvasive blood pressure measurement. Both theoretical and experimental studies are performed in the present work to investigate the dependence of the sub-harmonic generation on the overpressure with different excitation pressure amplitudes and pulse lengths. With4-MHz ultrasound excitation at an applied acoustic pressure amplitude of 0.24 MPa, the measured sub-harmonic amplitude exhibits a decreasing change as overpressure increases; while non-monotonic change is observed for the applied acoustic pressures of 0.36 MPa and 0.48 MPa, and the peak position in the curve of the sub-harmonic response versus the overpressure shifts toward higher overpressure as the excitation pressure amplitude increases. Furthermore, the exciting pulse with long duration could lead to a better sensitivity of the sub-harmonic response to overpressure. The measured results are explained by the numerical simulations based on the Marmottant model. The numerical simulations qualitatively accord with the measured results. This work might provide a preliminary proof for the optimization of the noninvasive blood pressure measurement through using sub-harmonic generation from microbubbles. 相似文献
13.
14.
15.
The stability enhancement of laser output power for the change of external cavity position in semiconductor lasers with optical feedback is observed by experiment. The relaxation oscillation frequency which plays an important role in the dynamics of the nonlinear system is also investigated as a function of the external cavity length. The period of the stability enhancement along the position of the external cavity is exactly coincident with the length corresponding to the relaxation oscillation frequency of the solitary laser. The experimental results are compared with theoretical and excellent coincidence between the two is found. 相似文献
16.
17.
18.
19.
Experimental Investigation of Chaos Synchronization in DFB Diode Lasers with Unsymmetrical Scheme 下载免费PDF全文
We experimentally generate high dimension chaotic waveforms with smooth spectrum using a distributed feedback (DFB) semiconductor laser with unidirectional fibre ring long-cavity feedback, and implement the stable chaos synchronization when the chaotic light is injected into a solitary DFB laser diode. The synchronization quality is investigated by time-domain and frequency-domain analysis separately, The frequency-domain analysis indicates that the synchronization has higher quality in the high frequency band. The influences of the injection strength and the frequency detuning on the synchronization are measured. Our experimental results show that the robust synchronization can be maintained with the optical frequency detuning from -11GHz to 40 GHz. 相似文献
20.
Experimental Investigation of Energy Level Dynamics in luminium Blocks with Temperature Distribution 下载免费PDF全文
Using temperature distribution as an external parameter to change symmetry and measuring frequency spectrum of acoustic resonances in aluminium blocks, we investigate the statistics and dynamics of energy levels in the chaotic billiards. To extract the resonances accurately and eliminate the influence of noise, a filter-diagonalization method for harmonic inversion is used to overcome low resolution of conventional fast Fourier transform method for low quantity factor resonance systems. We present an improved and feasible simulation method to study chaotic characteristic of quantum systems experimentally. 相似文献